2003-03-10
Mark A. McDaniel, Steven F. Maier and Gilles O. Einstein

Older adults have shown a strong interest in over-the-counter "brain boosters," many of which are marketed with grand claims touting their benefits. There are sound biochemical reasons for expecting some of these nutrients to be effective. In a review of published research, we found studies showing that some of these substances had robustly enhanced memory in lab animals and occasionally produced impressive improvements in humans as well. Nevertheless, there are numerous questions about the sample sizes in the studies, the generality of the results across different memory tests and populations, and other aspects of the procedures and data. These problems, in conjunction with a general lack of research demonstrating that the results can be replicated, dampen enthusiasm for the effectiveness of these nutrients in substantially arresting or reversing memory loss. Here is an abbreviated summary of the findings for six kinds of nonprescription compounds that are claimed to be memory enhancers and treatments for age-related memory decline.

Phosphatidylserine (PS)

A naturally occurring lipid, PS has been shown to reduce many consequences of aging on the neurons in older rats and mice and to restore their normal memory in a variety of tasks. Research on the impact in humans is limited, though. For older adults with moderate cognitive impairment, PS has produced modest increases in recall of word lists. Positive effects have not been as consistently reported for other memory tests.

Choline Compounds

Phosphatidylcholine, which is typically administered as lecithin, has not proved effective for improving memory in patients with probable Alzheimer' s disease. Research on citicoline is practically nonexistent, but one study reported a robust improvement in story recall for a small sample of normally aging older adults.

Piracetam

Developed in 1967, Piracetam has not been approved by the U.S. Food and Drug Administration, but it is sold in Europe and Mexico under several names (including Nootropil and Pirroxil). Animal studies suggest that the drug may improve neural transmission and synaptic activity and also combat age-related deterioration of neuronal membranes. But there is no clear sign of any cognitive benefits in patients with probable Alzheimer' s or adults with age-associated memory impairment.

Vinpocetine

An alkaloid derived from the periwinkle plant, vinpocetine increases blood circulation in the brain. In three studies of older adults with memory problems associated with poor brain circulation or dementia-related disease, vinpocetine produced improvements in performance on cognitive tests measuring attention, concentration and memory.

Acetyl-L-Carnitine (ALC)

An amino acid included in some "brain power" supplements sold in health food stores, ALC participates in cellular energy production, a process especially important to neurons. Animal studies show that ALC reverses age-related decline in the number of receptor molecules on neuronal membranes. But studies of patients with probable Alzheimer' s have reported only nominal advantages for ALC in a range of memory tests.

Antioxidants

Antioxidants such as vitamins E and C help to neutralize tissue-damaging free radicals, which become more prevalent with age. But studies have found that vitamin E does not offer significant memory benefits for patients with Alzheimer's or early Parkinson's disease. A combination of vitamins E and C did not improve college students' performance on several cognitive tasks.

A more detailed version of this article appeared as " Brain-Specific Nutrients: A Memory Cure?" by Mark A. McDaniel, Steven F. Maier and Gilles O. Einstein in Psychological Science in the Public Interest (May 2002). (Available at www.psychologicalscience.org/journals/pspi/3-1.html) McDaniel is chair of the department of psychology at the University of New Mexico. Maier is director of the Center for Neuroscience at the University of Colorado at Boulder. Einstein is chair of the department of psychology at Furman University.

http://www.sciam.com/print_version.cfm?articleID=00089D2E-26F6-1E64-A98A809EC5880105